Final answer:
The non-functional eyes of cavefish living in dark caves are an example of d.vestigial structures, which are remnants of evolutionary changes that show evidence of common ancestry and adaptation to the environment.
Step-by-step explanation:
The type of evidence of evolution exemplified by cavefish living in dark caves with non-functional eyes is vestigial structures. Vestigial structures are parts of an organism that have lost their original function through the process of evolution. Examples include the wings of flightless birds, pelvic bones in snakes and whales, and the non-functional eyes in cavefish. These structures indicate that an organism has changed from using the structure to not using it or using it for a different purpose.
Vestigial structures suggest a common ancestry and the process of adaptation to new environments. For instance, cavefish do not need sight in the absence of light, so over time, their eyes have become non-functional. This change is a clear sign of evolution, reflecting how organisms can lose unnecessary features as their environments change.
When comparing homologous and analogous structures, homologous structures are those that share a common ancestry and have evolved differently in various species, while analogous structures have evolved independently to serve similar functions. The sightless eyes of cavefish are a result of evolutionary changes from a common ancestor that did have functioning eyes, which makes them vestigial.